Are living trees warmer than dead trees?

[theatertech87]

Sounds like a stupid question but hear me out... Today in upstate New York we had a light bit of snow and temperatures hovering around the freezing point most of the morning. As I was driving around looking at jobs I noticed that there were a noticable number of standing dead ash (ash borer sucks fyi) that had a appreciable build up of snow on them, same thing with dead limbs on willows and some other trees (but the ash and willow were the most noticable) while virytally every norway/silver maple, poplar etc that I drove by were either devoid of snow or had a snow accumulation that was substaintally less than the dead trees.

Chatted it over with one of our arborists and our working theory is that the vascular system of living trees might be such that it pulls a small amount heat from the ground like a giant natural geothermal setup warming the branches of live trees just enough to melt the snow as it was falling; and that the air temperature conditions and soil temperatures today were just perfect enough to make it visible.

Anyone have any info to confirm or refute this theory?

 

[Rusticus]

I know water takes longer to cool and heat compared to air. That's why a fresh cut stump can feel cooler on a hot day or oak wilt can still spread in the vascular tissue in the hottest of days. Some of the best freeze protection for your landscape in the south is to irrigate your plants before a freeze.

 

[Tom Dunlap]

I’m just guessing…

Because of evapoytanspiration the air in the area is more humid. The same effect that swamp coolers have on cooling houses in hot dry regions

 

[pete3d]

I “believe” living trees are warmer than dead ones because here where the snow used to typically lie deep in the bush as winter advanced, one could see a snow free ring crater around the root flare of every living tree, and none around the dead trees. It was also clear that the bigger the tree the bigger the snow free “moat”.

 

[Tuebor]

Do the dead trees still have bark? Any chance the bark is loose, allowing cold air to get behind the bark, isolating it from the warmth of the trunk?

 

[Tom Dunlap]

Heat sinks in dark barked trees

 

[Bart_]

Dry wood has a bit of insulating power compered to moisture content wood which also has heat holding capacity probably also caused by the moisture content. My theory wetter wood slow to cool down hence has melting power. Similar conducting ground heat up into the lower trunk. It wouldn't take much cold air exposure to bring down dried dead wood surface temperature to freezing, or at least less exposure than wetter wood that's holding heat. (?)

 

[evo]

Yes they are, that and infrared has been toyed with for detecting decay.

Infrared Camera Measurements Reveal Diurnal Variation in the Effect of Mechanically Induced Internal Voids on Stem Temperatures of Small Trees Passively Heated by the Sun | Arboriculture & Urban Forestry

 

[Bart_]

Good point Evo I neglected to consider radiant sun heating in conjunction with heat conduction and heat capacity. A hollowed tree has less "stuff" to hold or conduct heat so changes surface temperature more easily. I think poorer wind cooling beats out sun heating because the denser wetter trees are staying warmer longer. (?)

 

[evo]

Good point Evo I neglected to consider radiant sun heating in conjunction with heat conduction and heat capacity. A hollowed tree has less "stuff" to hold or conduct heat so changes surface temperature more easily. I think poorer wind cooling beats out sun heating because the denser wetter trees are staying warmer longer. (?)

I’ve only very recently looked into it. There is a legal argument between a city and historical society I’m on the sidelines of, a concerned citizen has one of the IR units and took images of the tree. I can see its value yet since it’s a camera once crown density becomes a thing (conifer) it’s usefulness becomes an issue.

I can see it showing promise when needing to coarsely assess a number of trees within a time/budget constraint. Kinda like an advanced level 1 risk assessment. It probably can pickup loose bark too. Additionally it’s less damaging than sonic tomography as it’s entirely non invasive.

 

[theatertech87]

Yes they are, that and infrared has been toyed with for detecting decay.

Infrared Camera Measurements Reveal Diurnal Variation in the Effect of Mechanically Induced Internal Voids on Stem Temperatures of Small Trees Passively Heated by the Sun | Arboriculture & Urban Forestry

Interesting on the detecting decay side of things. The utility I used to trim for absolutely used infrared cameras to check vegetation growth, the trees would heat to as the conducted energy of they got too close to the wires. I only ever saw it used on voltages about 34kv